Effects of neoadjuvant chemotherapy with or without intensity-modulated radiotherapy for patients with rectal cancer

Neoadjuvant chemoradiotherapy (nCRT) followed by total mesorectal excision and adjuvant chemotherapy is the standard regimen for patients with locally advanced rectal cancer (LARC). However, whether and to which extent neoadjuvant radiotherapy could be removed from nCRT for patients with LARC is still unclear. This was a multicenter, retrospectively recruited, prospectively maintained cohort study. A propensity score matching model was employed to minimize potential confounding factors between subgroup patients treated with neoadjuvant chemotherapy (nCT) or nCRT. Overall survival (OS), disease-free survival (DFS), local recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) were assessed between subgroup patients by Kaplan-Meier analysis, log-rank test, and Cox regression model. In total, 3233 consecutive patients, consist of 571 nCT and 2662 nCRT-treated cases, were included. After propensity score matching (1:4), 565 nCT-treated patients were matched to 1852 nCRT-treated patients. Compared with nCT, nCRT treatment indeed decreased 3-y local recurrence (10.0% vs 6.6%, P = .026), but had no impact on OS, DFS and DMFS (all P > .05) for LARC. Stratified analysis further confirmed that nCRT treatment was associated with higher 3-y LRFS and 3-y DFS than nCT treatment for baseline high-risk subgroup (cT4, cN+, and cIII stage) patients (all P < .05). Conversely, for the baseline low-risk subgroup patients (cT3, cN0, and cII stage), nCRT and nCT treatment had similar 3-y OS, LRFS, DFS, and DMFS (all P > .05). The administration of neoadjuvant radiotherapy for LARC patients might be determined by baseline risk classification, the high-risk individuals could be delivered while low-risk patients might be omitted.